Coupling out of light from lighting modules (in particular so-called “light engines”) that typically include a substrate populated with light-emitting diodes can be limited by a deficient reflectivity of the substrate. In order to realize a high degree of coupling out of light in the case of such lighting modules, the substrate can be covered with a light-reflecting layer.
In this regard, it is known, after populating and making contact with the light-emitting diodes, to pot the substrate alongside the light-emitting diodes with silicone, wherein the silicone contains a reflective filling material such as titanium oxide. In this case, problems often arise on account of contamination of emission surfaces of the light-emitting diodes by silicone spatter and light losses caused thereby. Furthermore, a deficient wetting of specific substrate regions can occur depending on a surface roughness and surface energy. Moreover, specific regions may be wetted to a great extent and the silicone may “creep up” on walls and electrical lines (e.g. bonding wires) of the light-emitting diodes onto the emitter area, particularly when flat LED chips are used.
Use of a large-area silver layer as a light-reflecting layer is also known, which layer, however, has to be protected against corrosion (“tarnish”) and migration.